What evidence do geologists have that Earth was once hotter than it is today?
What will be an ideal response?
Answer: 1. The current heat flow from within Earth is approximately twice as high as can be accounted for by present-day radioactive decay in the crust and mantle. This suggests excess heat that remains from processes active in the past when Earth was hotter.
2. Ultramafic lava flows are found on Earth only among rocks more than 3 billion years old. Experiments reveal that these unique lava flows, the only known extrusive equivalents of peridotite, could only form at mantle temperatures several hundred degrees hotter than those estimated today.
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How much gravitational force acts on a 500-N woman standing on Earth's surface?
A. 250 N. B. more than 500 N. C. 500 N. D. 50 N.
Collectively, the shield and platform of a continent are known as a(n) ____________________. Fill in the blank(s) with the appropriate word(s)
What is the difference between adhesion and cohesion?
A) Adhesion is the tendency of water molecules to stick to each other while cohesion is the tendency of water molecules to stick to other solids. B) Adhesion allows water to create a surface tension while cohesion causes capillary action. C) Adhesion is the tendency of water molecules to stick to solids while cohesion is the property that allows water molecules to stick to each other. D) Adhesion and cohesion are synonymous terms.
Stationary fronts
A) are usually cloudless. B) are the same as occluded fronts. C) occur when two cold fronts meet. D) occur inside a single air mass. E) are often accompanied by precipitation.